Crosslinkable waterborne dispersions of hydroxy functional polydiene polymers and amino resins

ABSTRACT

A crosslinkable waterborne dispersion of a hydroxy functional polydiene polymer composition which comprises: (a) 10 to 65% w of a hydroxy functional polydiene polymer, (b) 0.2 to 25% w of a compatible amino resin, (c) 0.1 to 10% w of a surfactant which is nonionic or anionic and has a volatile cation, and (d) the balance water. The invention also describes a water-continuous process and an inversion processes for making such dispersions.

This is a continuation of application Ser. No. 08/479,583, filed Jun. 7,1995 now abandoned which is a continuation of Ser. No. 08/277,375, filedJul. 18, 1994, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to waterborne dispersions of hydroxy functionalpolydiene polymers. More specifically, the invention relates towaterborne dispersions of such polymers and amino resins which can becrosslinked to make cured films, coatings, adhesives, sealants, caulks,binders and modifiers for asphalt.

Hydroxy functional polydiene polymers are well known. It has been shownthat formulations containing these polymers, a melamine resin, and anacid catalyst can be cured by baking under normal bake conditions. Ifsuch formulations could be dispersed in water, the utility of thesepolymers would be greatly broadened. This would allow preparation of lowviscosity, waterborne formulations having very low volatile organiccompound (VOC) contents. By adding waterborne hydroxy functionalpolydiene polymer dispersions to other water-based products havingcompatible surfactant systems, these polymers could be used to modifyother types of resins and this could be done without concern about phaseseparation due to incompatibility of the hydroxy functional polydienepolymers and solvent-based resins.

It is one object of the present invention to provide a crosslinkablewaterborne dispersion of hydroxy functional polydiene polymers and aminoresins. Another object of this invention is to provide a method formaking such crosslinkable waterborne dispersions.

SUMMARY OF THE INVENTION

The present invention provides a water dispersion of a crosslinkablehydroxy functional polydiene polymer composition which comprises:

(a) 10 to 65% by weight (% w) of a hydroxy functional polydiene polymer,

(b) 0.2 to 25% w of a compatible amino resin,

(c) 0.1 to 10% w of a nonionic surfactant or an anionic suffactanthaving a volatile cation, and

(d) the balance water.

In a preferred embodiment of the present invention, the compatible aminoresin is a butylated amino resin and the surfactant is an anionicsurfactant composed of an amine salt of an acid which can be used tocatalyze the crosslinking of the polymer and the amino resin such asparatoluene sulfonic acid or dodecylbenzene sulfonic acid.

This invention also describes processes for making such crosslinkablewaterborne dispersions. One method involves making a hot aqueoussolution of the surfactant, adding a mixture of a hydroxy functionalpolydiene polymer and a compatible amino resin to the hot aqueoussolution, and then mixing the components under high shear conditions.The preferred method involves mixing together at a temperature of 25° to90° C. with vigorous agitation a hydroxy functional polydiene polymer,an amino resin, and the desired surfactant, and then adding water to themixture slowly over a period of at least 15 minutes.

DETAILED DESCRIPTION OF THE INVENTION

The hydroxy functional polydiene polymers of the present invention aremonools, diols, and polyols of hydrogenated and unhydrogenated lowmolecular weight diene homopolymers and copolymers with more than onediene and/or a vinyl aromatic hydrocarbon. Such copolymers will usuallybe random copolymers or tapered block copolymers since it is difficultto make low molecular weight copolymers with a sharp division betweenblocks because the crossover reaction from one monomer to the other isusually slow compared to the progagation reaction. Suitable polymersinclude monools, diols, and polyols of low molecular weightpolybutadiene and polyisoprene and their copolymers with styrene, eitherhydrogenated or unhydrogenated.

Hydrogenated polybutadiene diols are preferred for use herein becausethey are easily prepared, they have low glass transition temperature,and they have excellent weatherability. The diols, dihydroxylatedpolybutadienes, are synthesized by anionic polymerization of conjugateddiene hydrocarbons with lithium initiators. Monools and polyols can alsobe synthesized in the same manner. This process is well known asdescribed in U.S. Pat. Nos. 4,039,593 and Re. 27,145 which descriptionsare incorporated herein by reference..Polymerization commences with amonolithium, dilithium, or polylithium initiator which builds a livingpolymer backbone at each lithium site. Typical monolithium livingpolymer structures containing conjugated diene hydrocarbons are:

    ______________________________________                                        X-B-Li              X-B.sub.1 -B.sub.2 -Li                                    X-A-B-Li            X-A-B.sub.1 -B.sub.2 -Li                                  X-A-B-A-Li                                                                    ______________________________________                                    

wherein B represents polymerized units of one or more conjugated dienehydrocarbons such as butadiene or isoprene, A represents polymerizedunits of one or more vinyl aromatic compounds such as styrene, and X isthe residue of a monolithium initiator such as sec-butyllithium. B canalso be a copolymer of a conjugated diene and a vinyl aromatic compound.B₁ and B₂ are formed of different dienes.

The anionic polymerization of the conjugated diene hydrocarbons istypically carried out in a hydrocarbon solvent containing a structuremodifier such as diethylether or glyme (1,2-diethoxyethane) to obtainthe desired amount of 1,4-addition. As described in Re 27,145 which isincorporated by reference herein, the level of 1,2-addition of abutadiene polymer or copolymer can greatly affect elastomeric propertiesafter hydrogenation. The 1,2-addition of 1,3-butadiene polymers havingterminal functional groups significantly and surprisingly influences theviscosity of the polymers. A 1,2-addition of about 40% is achievedduring polymerization at 50° C. with about 6% by volume of diethyletheror about 1000 ppm of glyme in the polymerization solvent.

The present invention also contemplates linear unsaturated orhydrogenated isoprene polymers having one to two terminal hydroxy groupsper molecule and also such polymers having additional hydroxy groups.Preferably, the isoprene polymers have greater than 80% 1,4-addition ofthe isoprene and hydrogenation of at least 90% of the polymerizedisoprene. The polymers are preferably prepared by anionic polymerizationin the absence of microstructure modifiers that increase 3,4-addition ofthe isoprene.

The hydroxy functional polydiene polymers may have molecular weights offrom about 1,000 to about 3,000,000. Lower molecular weights requireexcessive crosslinking whereas higher molecular weights cause very highviscosity, making processing very difficult. More preferably, thepolymer is one having a molecular weight of from about 2,000 to about1,000,000. Most preferably, the polymer is one having a molecular weightof from about 3,000 to about 200,000 because this offers the bestbalance between cost, ability to use the mildest curing conditions andachieving good processing behavior.

In general, when solution anionic techniques are used, conjugateddiolefin polymers, polydienes, are prepared by contacting the monomer tobe polymerized with an anionic polymerization initiator such as group IAmetals, their alkyls, amides, silanolates, napthalides, biphenyls andanthracenyl derivatives. It is preferred to use an organo alkali metal(such as sodium or potassium) compound in a suitable solvent at atemperature within the range from about -150° C. to about 300° C.,preferably at a temperature within the range from about 0° C. to about100° C. Particularly effective anionic polymerization initiators areorgano lithium compounds having the general formula:

    RLi.sub.n

wherein R is an aliphatic, cycloaliphatic, aromatic or alkyl-substitutedaromatic hydrocarbon radical having from 1 to about 20 carbon atoms andn is an integer of 1 to 4.

Conjugated diolefins which may be polymerized anionically include thoseconjugated diolefins containing from about 4 to about 24 carbon atomssuch as 1,3-butadiene, isoprene, piperylene, methylpentadiene,phenylbutadiene, 3,4-dimethyl- 1,3-hexadiene, 4,5-diethyl-1,3-octadieneand the like. Isoprene and butadiene are the preferred conjugated dienemonomers for use in the present invention because of their low cost andready availability. The conjugated diolefins which may be used in thepresent invention include isoprene (2-methyl-1,3-butadiene),2-ethyl-1,3-butadiene, 2-propyl-1,3-butadiene, 2-butyl-1,3-butadiene,2-pentyl-1,3-butadiene(2-amyl-1,3-butadiene), 2-hexyl-1,3-butadiene,2-heptyl-1,3-butadien 2-octyl-1,3-butadiene, 2-nonyl-1,3-butadiene,2-decyl-1,3-butadiene,2-dodecyl-1,3-butadiene,2-tetradecyl-1,3-butadiene, 2-hexadecyl-1,3-butadiene,2-isoamyl-1,3-butadiene, 2-phenyl -1,3-butadiene,2-methyl-1,3-pentadiene, 2-methyl-1,3-hexadiene,2-methyl-1,3-heptadiene, 2-methyl-1,3-octadiene,2-methyl-6-methylene-2,7-octadiene (myrcene), 2-methyl-1,3-nonyldiene,2-methyl-1,3-decyldiene, and 2-methyl-1,3-dodecyldiene, as well as the2-ethyl, 2-propyl, 2-butyl, 2-pentyl, 2-hexyl, 2-heptyl, 2-octyl,2-nonyl, 2-decyl, 2-dodecyl, 2-tetradecyl, 2-hexadecyl, 2-isoamyl and2-phenyl versions of all of these dienes. Also included are1,3-butadiene, piperylene, 4,5-diethyl- 1,3-octadiene and the like.Di-substituted conjugated diolefins which may be used include2,3-dialkyl-substituted conjugated diolefins such as2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-pentadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-diethyl-1,3 -heptadiene,2,3-dimethyl-1,3-octadiene and the like and 2,3-fluoro-substitutedconjugated diolefins such as 2,3-difluoro-1,3-butadiene,2,3-difluoro-1,3-pentadiene, 2,3-difluoro-1,3-hexadiene,2,3-difluoro-1,3-heptadiene, 2,3-fluoro-1,3-octadiene and the like.Alkenyl aromatic hydrocarbons which may be copolymerized include vinylaryl compounds such as styrene, various alkyl-substituted styrenes,alkoxy-substituted styrenes, vinyl napthalene, alkyl-substituted vinylnapthalenes and the like.

In general, any of the solvents known in the prior art to be useful inthe preparation of such polymers may be used. Suitable solvents, then,including straight--and branched chain hydrocarbons such as pentane,hexane, heptane, octane and the like, as well as, alkyl-substitutedderivatives thereof; cycloaliphatic hydrocarbons such as cyclopentane,cyclohexane, cycloheptane and the like, as well as alkyl-substitutedderivatives thereof; aromatic and alkyl-substituted aromatichydrocarbons such as benzene, naphthalene, toluene, xylene and the like;hydrogenated aromatic hydrocarbons such as tetralin, decalin and thelike; linear and cyclic ethers such as methyl ether, methylethyl ether,diethyl ether, tetrahydrofuran and the like.

More specifically, the polymers of the present invention are made by theanionic polymerization of conjugated diene monomers in a hydrocarbonsolvent at a temperature between 0° and 100° C. using an alkyl lithiuminitiator.

The termination of living anionic polymers to form functional end groupsis described in U.S. Pat. Nos. 4,417,029, 4,518,753, and 4,753,991,which are herein incorporated by reference. Of particular interest forthe present invention are terminal hydroxyl groups. A monool has onesuch terminal hydroxy group on only one end of the polymer. A diol has ahydroxy group on each end of the polymer. Polyols are such polymerswhich have more than two hydroxy groups. Such polymers may be linearpolymers with internal hydroxy groups in addition to the terminalhydroxy groups or they may be radial or star polymers having multiplearms of polydiene radiating from a central core and having terminalhydroxy groups thereon.

Anionic polymerization is often terminated by addition of water toremove the lithium as lithium hydroxide (LiOH) or by addition of analcohol (ROH) to remove the lithium as a lithium alkoxide (LiOR). Forpolymers having terminal functional groups, the living polymer chainsare preferably terminated with hydroxyl, carboxyl, phenol, epoxy, oramine groups by reaction with ethylene oxide, carbon dioxide, aprotected hydroxystyrene monomer, ethylene oxide plus epichlorohydrin,or the amine compounds listed in U.S Pat. No. 4,791,174, respectively.The termination step can result in release of fine particles of lithiumbases as described in U.S. Pat. No. 5,166,277 which is incorporated byreference herein. The lithium bases may interfere with hydrogenation ofthe polymer and preferably are removed.

Hydrogenation of at least 90%, preferably at least 95%, of theunsaturation in the low molecular weight hydroxy functional polydienepolymers is achieved with nickel catalysts as described in U.S. Pat.Nos. Re. 27,145 and 4,970,254 and U.S. patent application Ser. No.07/785715 which are incorporated by reference herein. The preferrednickel catalyst is a mixture of nickel 2-ethylhexanoate andtriethylaluminum.

Molecular weights of linear polymers or unassembled linear segments ofpolymers such as mono-, di-, triblock, etc., arms of star polymersbefore coupling are conveniently measured by Gel PermeationChromatography (GPC), where the GPC system has been appropriatelycalibrated. For polymers of the type described herein, the suitablecalibration standards are narrow molecular weight distributionpolystyrene polymers. For anionically polymerized linear polymers, thepolymer is essentially monodisperse and it is both convenient andadequately descriptive to report the "peak" molecular weight of thenarrow molecular weight distribution observed. The peak molecular weightis usually the molecular weight of the main species shown on thechromatograph. For materials to be used in the columns of the GPC,styrene-divinyl benzene gels or silica gels are commonly used and areexcellent materials. Tetrahydrofuran is an excellent solvent forpolymers of the type described herein. Ultraviolet or refractive indexdetectors may be used.

Measurement of the true molecular weight of a coupled star polymer isnot as straightforward or as easy to make using GPC. This is because thestar shaped molecules do not separate and elute through the packed GPCcolumns in the same manner as do the linear polymers used for thecalibration. Hence, the time of arrival at an ultraviolet or refractiveindex detector is not a good indicator of the molecular weight. A goodmethod to use for a star polymer is to measure the weight averagemolecular weight by light scattering techniques. The sample is dissolvedin a suitable solvent at a concentration less than 1.0 gram of sampleper 100 milliliters of solvent and filtered using a syringe and porousmembrane filters of less than 0.5 microns pore size directly into thelight scattering cell. The light scattering measurements are performedas a function of scattering angle, polymer concentration and polymersize using standard procedures. The differential refractive index (DRI)of the sample is measured at the same wave length and in the samesolvent used for the light scattering. The following references areherein incorporated by reference:

1. Modem Size-Exclusion Liquid Chromatography, M. W. Yau, J. J.Kirkland, D. D. Bly, John Wiley and Sons, New York, New York, 1979.

2. Light Scattering From Polymer Solutions, M. B. Huglin, ed., AcademicPress, New York, New York, 1972.

3. W. K. Kai and A. J. Havlik, Applied Optics, 12, 541 (1973).

4. M. L. McConnell, American Laboratory, 63, May, 1978.

The crosslinking agents which are useful in the present invention areamino resins. For the purposes of this invention, an amino resin is aresin made by reaction of a material bearing NH groups with a carbonylcompound and an alcohol. The NH bearing material is commonly urea,melamine, benzoguanamine, glycoluril, cyclic ureas, thioureas,guanidines, urethanes, cyanamides, etc. The most common carbonylcomponent is formaldehyde and other carbonyl compounds include higheraldehydes and ketones. The most commonly used alcohols are methanol,ethanol, and butanol. Other alcohols include propanol, hexanol, etc.American Cyanamid (renamed CYTEC) sells a variety of these amino resins,as do other manufacturers. American Cyanamid's literature describesthree classes or "types" of amino resins that they offer for sale.##STR1## where Y is the material that bore the NH groups, the carbonylsource was formaldehyde and R is the alkyl group from the alcohol usedfor alkylation. Although this type of description depicts the aminoresins as monomeric material of only one pure type, the commercialresins exist as mixtures of monomers, dimers, trimers, etc. and anygiven resin may have some character of the other types. Directs,trimers, etc. also contain methylene or ether bridges. Generally, type 1amino resins are preferred in the present invention.

The amino resin must be compatible with the hydroxy functional polydienepolymer. A compatible amino resin is defined as one which gives a phasestable blend with the polydiene polymer at the desired concentration andat the temperature to which the mixture will be heated when thedispersion in water is actually being made. We have found that it isbest that the amino resin be butylated to a significant extent forproper compatibility with the polydiene polymers, i.e., the R groupsmust be butyl groups or at least primarily butyl groups.

For example, the following type 1 amino resins can be used to achievethe purpose of the present invention: CYMEL 1156--amelamine-formaldehyde resin where R is C₄ H₉, CYMEL 1170--aglycoluril-formaldehyde resin where R is C₄ H₉, CYMEL 1141--a carboxylmodified amino resin where R is a mixture of CH₃ and i-C₄ H₉, and BEETLE80--a urea-formaldehyde resin where R is C₄ H₉. All of these productsare made by American Cyanamid Company and are described in itspublication 50 Years of Amino Coating Resins, edited and written byAlbert J. Kirsch, published in 1986 along with other amino resins usefulin the present invention. ##STR2##

CYMEL 1170 is the following glycoluril-formaldehyde resin where R is C₄H₉ : Another is BEETLE® 80 urea-formaldehyde resin where R is C₄ H₉whose ideal monomeric structure is depicted: ##STR3##

In the crosslinkable waterborne dispersion, the hydroxy functionalpolydiene polymer should comprise from 10 to 65% by weight (% w) of thetotal dispersion. The amino resin should be used in a ratio of 98:2 to60:40 by weight with the polydiene polymer. Thus, the amino resin willcomprise from 0.2 to 25 % w of the dispersion. The dispersion will alsorequire a surfactant, preferably an amine salt of an acid. Thesurfactant is used in an amount from 0.1 to 10% w.

If less than 10% w of the polymer is used, then the solids content ofthe dispersion will be uneconomically low and if more than 65% w isused, then the viscosity of the dispersion (if it can be made at all)will be too high. If less than 0.2% w of the amino resin is used, thenthe composition will not crosslink and if more than 25% w is used, thencompatibility with the polydiene polymer will be poor and poor qualitycured films will result. If less than 0.1% w of the surfactant is used,then stable dispersions in water cannot be made and if more than 10% wof the surfactant is used, then cured films will have high moisturesensitivity. The balance of the dispersion is water.

Since the hydroxy functional polydiene polymer and its mixtures withmelamine resin are hydrophobic and insoluble in water, a surfactant mustbe used to form a stable dispersion of the polymer and melamine inwater. A wide variety of nonionic and anionic surfactants would besuitable. There are almost no restrictions on the type of nonionicsurfactant which could be considered. The only restriction on the typeof anionic surfactant is that the cation used to neutralize the acid onthe hydrophobe must be volatile enough to leave the film during themelamine cure. Otherwise, a nonvolatile cation would neutralize thestrong acid needed to catalyze the melamine curing reaction, therebyinhibiting cure. In fact, the preferred anionic surfactant is the onemade by neutralizing the strong acid needed to catalyze the curingreaction with a volatile amine. The amine-neutralized acid serves as thesurfactant stabilizing the dispersion and then, after the film is cast,the amine volatilizes, regenerating the acid which catalyzes themelamine cure.

Surfactants are molecules which have a hydrophobic portion (A) and ahydrophilic portion (B). They may have the structure A-B, A-B-A, B-A-B,etc. Typically, the hydrophobic section can be an alkyl group (e.g.C₁₂), an alkyl/aryl group (e.g. octylphenol), a polypropylene oxideblock, a polydimethylsiloxane block or a fluorocarbon. The hydrophilicblock of a nonionic surfactant is a water soluble block, typically apolyethylene oxide block or a hydroxylated polymer block. Thehydrophilic block of an anionic surfactant is typically an acid groupionized with a base. Typical acid groups are carboxylic acids, sulfonicacids or phosphoric acids. Typical bases used to ionize the acids areNaOH, KOH, NH₄ OH and a variety of tertiary amines, such as triethylamine, triisopropyl amine, dimethyl ethanol amine, methyl diethanolamine and the like. Nonvolatile bases such as NaOH and KOH should beavoided in this invention since they will neutralize the strong acidneeded to catalyze the melamine curing reaction.

A proton-donating acid catalyst is required to achieve the purposes ofthe present invention, i.e., crosslink the polymer using the aminoresins described above. It is normal that the amount of the acidcatalyst used range from about 0.1 to about 4% w of the polymer/amineresin mixture to be certain there is sufficient acid but an excess canbe undesirable. Most preferably, from about 0.5 to about 2% w of thepolymer/amine resin is used. The presence of a strong proton-donatingacid is normally required to catalyze the crosslinking reaction of manyamino resins which are useful in the present invention. However, somemedium strength and even relatively weak acids may also be effectivedepending upon the amino resins used. Generally, the most activecatalyst are those with the lowest pKa values. The following list ofacid catalysts which may be used in the present invention is arrangedaccording to increasing pKa value: mineral acids, Cycat® 4040 catalyst(p-toluene sulfonic acid), Cycat® 500 catalyst (dinonylnaphthalenedisulfonic acid), Cycat® 600 catalyst (dodecyl benzene sulfonic acid),oxalic acid, maleic acid, hexamic acid, phosphoric acid, Cycat® 296-9catalyst (dimethyl acid pyrophosphate), phthalic acid and acrylic acid(copolymerized in polymer). Other acids which may be used are describedin the aforementioned American Cyanamid Company publication. Also, 3MBrand Resin Catalyst FC-520 (diethylammonium salt of trifluoromethanesulfonic acid) may be used. Cycat® 600 was found to be a very usefulcatalyst.

It is highly preferred that the acid which is used in the surfactant bean acid which is capable of catalyzing the crosslinking of the polydienepolymer and the amino resins. Such acids are described above and includethe various sulfonic acids described in the preceding paragraph. Afterthe dispersion is applied to a substrate, usually after being formulatedfor a specific application such as a coating, adhesive or sealant, thevolatile amine in the surfactant will evaporate into the atmosphere,freeing the acid to catalyze the curing reaction between the amino resinand the polydiene polymer. This is highly advantageous because iteliminates the cost of adding separate surfactant and acid catalystcomponents to the process for making these dispersions and also becauseit is a very simple and very effective approach to preparing dispersionsin water. However, it is within the scope of this invention to use anonionic or anionic surfactant to make the dispersion of polydienepolymer/amino resin which does not utilize the amine salt of the acidwhich can catalyze the curing reaction. In this case, of course, theacid catalyst would then have to be added to the dispersion.

The curing generally occurs within 5 seconds to 60 minutes, preferably10 to 30 minutes, once the polydiene polymer and amino resin are exposedto the catalyst and usually high temperature. However, curing couldoccur at near ambient temperature over a period of up to 60 days such asfor construction mastics, laminating adhesives and flexible packaginglaminating adhesives.

The cure temperature generally ranges from -5° C. to 400° C. 100° to300° C. is preferred and 100° to 200° C. is most preferred. In someapplications, such as coil coating, curing is accomplished throughheating to a maximum substrate surface temperature of up to 300° C. Ifthis cure schedule is used, the time at this temperature is generallyvery short (on the order of 5 seconds) and cure continues as the surfacecools.

Premature crosslinking is prevented by blocking the acid catalyst as anamine salt. The most preferred amine used in this work is triethylamine.Other blocking agents include triisopropylamine, dimethylethanolamine,methyldiethanolamine, diethylethanolmine, triethanolarnine,diisopropanolamine, morpholine and 2-amino-2-methyl-1-propanol, water,primary, secondary and tertiary alcohols, as well as others described inthe aforementioned American Cyanamid Company publication.

One method for making the dispersions of the present invention is thewater-continuous process. In this process, a blend of the polydienepolymer and the amino resin is heated to reduce viscosity so it can behandled easily, usually to about 25° to about 80° C., is added to a hotwater solution of the surfactant and dispersed preferably under highshear conditions. This process is easy to use because the viscosity isalways low since water is always the continuous phase.

Dispersions according to the present invention can also be made by theinversion process. In this process, the polydiene polymer and the aminoresin are mixed at about 25° to about 90° C. with, for example, astirrer composed of two 4-blade propellers on a shaft rotating at about500 to 5000 rpm. Water is added slowly over a period of at least 15minutes. The mix is organic-continuous initially. As water is slowlyadded, the viscosity increases. The viscosity becomes very high as theinversion point is approached. As more water is added, the dispersioninverts from organic-continuous to water-continuous and the viscositydrops dramatically. This process is preferred over the water-continuousprocess because it usually gives a better, smaller particle size, morestable dispersion.

The present invention has many advantages. The main advantage is thatthe products can be applied at ambient temperatures as low viscosityliquids without the use of large quantities of solvents. Anotheradvantage is that curing can be accomplished with relatively simpleequipment and without additional formulation ingredients required forsuch crosslinking. The present invention also allows easy cure ofcoatings on irregularly-shaped objects. The waterborne dispersions canalso be used as additives to other waterborne polymers having compatiblesurfactant systems to enhance specific properties such as toughness andflexibility.

The crosslinked materials of the present invention are useful inadhesives (including pressure sensitive adhesives, contact adhesives,laminating adhesives and assembly adhesives), sealants, coatings, films(such as those requiring heat and solvent resistance), printing plates,fibers, dipped goods (such as gloves), and as modifiers for polyesters,polyethers, polyamides and epoxies. In addition to the polydiene polymerand any curing aids or agents, products formulated to meet performancerequirements for particular applications may include variouscombinations of ingredients including adhesion promoting or tackifyingresins, plasticizers, fillers, solvents, stabilizers, etc.

Adhesive compositions of the present invention may be utilized as manydifferent kinds of adhesives, for example, laminating adhesives,flexible packaging laminating adhesives, pressure sensitive adhesivesand tie layers. The adhesive can consist of a formulated compositioncontaining a significant portion of the polydiene polymer along withother known adhesive composition components.

One preferred use of the present formulation is the preparation ofpressure-sensitive adhesive tapes and labels. Normally, the polymerdispersions of this invention will be mixed with a dispersion of acompatible tackifying resin prior to application to the backing. Thepressure-sensitive adhesive tape comprises a flexible backing sheet anda layer of the adhesive composition of the instant invention coated onone side of the backing sheet. The backing sheet may be a plastic film,paper or any other suitable material and the tape may include variousother layers or coatings, such as primers, release coatings and thelike, which are used in the manufacture of pressure-sensitive adhesivetapes. Alternatively, when the amount of tackifying resin is near zero,the compositions of the present invention may be used for a sizing agentor saturant for paper, fabric or other fibers, as a rubbery article(such as a glove), for toughening asphalt, and the like.

Another preferred use of the present formulation is the preparation ofcoatings for substrates that can be baked at the temperatures describedabove. Such coatings are expected to be of particular importance forautomotive and general metal finishes, especially coil coats. As will beseen in the following examples, coatings can be prepared with excellentcolor, clarity, hardness and adhesion. If substantially saturatedpolymers are used, the weatherability of the resulting films is expectedto be excellent.

EXAMPLES

Two hydrogenated polybutadiene diol polymers having a primary hydroxylfunctional group on each end were used to demonstrate this invention.Both were made by anionic polymerization. Polymer A has a GPC peakmolecular weight (MW) of 2000 and the unhydrogenated polybutadiene diolprecursor had 85% 1,2-butadiene addition. Polymer B has a MW of 4000 andthe precursor had 40% 1,2 addition.

The acid used was CYCAT 600, dodecyl benzene sulfonic acid (a 70% weightsolution in isopropyl alcohol). Diethanol amine (DEA), triethylamine(TEA), or ammonia was used to neutralize the acid. Three melamine resinswere tested in the formulation, a fully methylated melamine (CYMEL 303),a fully butylated glycoluril-formaldehyde (CYMEL 1170), and an acidfunctional, methylated/butylated melamine (CYMEL 1141). A siliconeantifoam (BYK-034) was used in formulations where foaming was a problem.

Example 1

To minimize the partial incompatibility of Polymers A and B with theamino resin CYMEL 1141, the polymer and melamine were partially reactedprior to dispersing them in water. Enough reaction must be accomplishedthat the polymer and CYMEL 1141 are compatible during cure but too muchreaction will cause the mix to be high in viscosity, matting inversionto the water dispersion difficult. The following procedure wassatisfactory.

In this procedure, 80 parts by weight (pbw) polymer, 20 pbw CYMEL 1141,and 18 pbw BUTYL OXITOL from Shell Chemical used to improve thefilm-forming capability of the dispersion upon drying, were heated to80° C. in a resin kettle. While stirring, 0.4 pbw CYCAT 600 diluted with2 pbw BUTYL OXITOL was added and the mixture was cooked for 2 hours. Thesurfactant was prepared by mixing 1.6 pbw CYCAT 600 and 2 pbw TEA in abottle with 5 pbw water. This surfactant was added to the partiallyreacted polymer/CYMEL 1141 at 70° C. while stirring at 2,000 rpm with astirrer having dual 4-bladed propellers. Blowing ambient temperature airon the can helped control the temperature rise due to viscous heating.Deionized water was then slowly added. Since some of the volatile TEAwas lost during the dispersion, 2% by weight TEA was in the water beingadded to the mix in order to maintain a pH of at least 9. If the wateris added too quickly (in less than about 5 minutes), a dispersion isobtained which creams upon standing overnight (probably because theparticle size is too large). However, if the water is added over about a15 to 30 minute period, a very nice stable dispersion is obtained.

The dispersions made with both Polymers A and B were low viscosity,milky white dispersions which remained stable upon storage for at leastseveral weeks. The dispersion based on Polymer A developed a smallamount of coagulum upon storage. The dispersion based on Polymer B didnot show any coagulation or phase separation. When the dispersions werecast on aluminum and baked for 20 minutes at 175° C., both polymers Aand B gave clear, glossy, colorless, peelable, elastomeric coatings.Although they were not tacky, they had the high coefficient of frictioncharacteristic of rubbery films.

Example 2

Composition #1 in the table is a dispersion of Polymer A in water usingthe acid, neutralized with diethanol amine (DEA), as the surfactant. Tomake this dispersion, 2 grams of CYCAT 600 was added to 100 grams ofdeionized water. This was heated to 60° C. and 2.55 grams DEA was added(giving a pH of about 9). 100 grams of Polymer A, preheated to 80° C. toreduce its viscosity, was then poured into the soapy water whileshearing the blend using a Silverson mixer-emulsifier rotating at about8000 rpm. Since it foamed badly, 0.1 gram of BYK 034 antifoam was addedto reduce foaming. This dispersion, made by the water-continuous processwithout an amino resin, was a fairly thick, creamy, white dispersion.After one month storage at ambient temperature, it showed some creamingbut no coagulation.

Composition #2 in the table is a dispersion of 80% w Polymer A with 20%w CYMEL 1170 using CYCAT 600 neutralized with ammonia as the surfactant.Polymer A and CYMEL 1170 were mixed manually at about 80° C. beforebeing added to the soapy water. The dispersion was made with theSilverson mixer/emulsifier using the same procedure as with Composition#1. Composition #2 also was a thick, creamy, white dispersion whichshowed little change upon storage at ambient temperature for one month.An attempt to make Composition #2 using CYMEL 303 instead of CYMEL 1170was unsuccessful because the blend of Polymer A with CYMEL 303 wasincompatible and phase separated before being added to the soapy water.

    ______________________________________                                        Water Dispersions Made With Polymer A                                         Composition, % w   1       2                                                  ______________________________________                                        Polymer A          100     80                                                 CYMEL 1170                 20                                                 CYCAT 600          2       2                                                  DIETHANOL AMINE    2.55                                                       AMMONIA                    2                                                  BYK 034            0.1     0.1                                                Water              100     100                                                ______________________________________                                    

Example 3

Composition #2 of Example 2 was also dispersed using the inversionprocess. Eighty grams of Polymer A and 20 grams of CYMEL 1170 were mixedin a pint can on a hot plate at 60° C. While stirring with two 4-bladedpropellers on a shaft rotating at about 2000 rpm, a blend of 2 gramsCYCAT 600, 2 grams ammonia, 0.1 gram BYK 034 and 5 grams water wasadded. Water, containing 1% w ammonia, was then added slowly over abouta 30 minute period, to make the dispersion by the inversion process.This gave an excellent dispersion. It was a low viscosity, whitedispersion which showed no creaming or coagulation after storage atambient temperature for one month.

We claim:
 1. A stable water dispersion of a hydroxy functional polydienepolymer composition which was crosslinked in water in the absence of anorganic solvent which consists essentially of:a) 10 to 65 percent w of ahydroxy functional polydiene polymer, b) 0.2 to 25 percent w of acompatible amino resin, c) 0.1 to 10 percent w of a surfactant which isnonionic or anionic having a volatile cation, and d) the balance water.2. The dispersion of claim 1 wherein the amino resin is a butylatedamino resin.
 3. The dispersion of claim 1 wherein the surfactant is anamine salt of an organic add.
 4. The dispersion of claim 3 wherein theacid is an acid which can be used to catalyze the crosslinking of thepolymer and the amino resin.
 5. The dispersion of claim 3 wherein theamine is a tertiary amine selected from the group consisting oftriethylamine, triisopropylamine, methytdiethanolamine anddimethylethanolamine.
 6. The dispersion of claim 1 wherein aproton-donating catalyst is included in the composition.
 7. Acrosslinked coating comprising the dispersion of claim 6 which isapplied to a substrate.
 8. A crosslinked adhesive comprising thedispersion of claim 6 which is applied to a substrate.
 9. A crosslinkedsealant comprising the dispersion of claim 6 which is applied to asubstrate.
 10. The dispersion of claim 1 wherein the polymer has a peakmolecular weight as determined by gel permeation chromatography of from2,000 to 1,000,000.
 11. The water dispersion of claim 1 wherein thepolymer has one terminal hydroxy group per molecule.
 12. The waterdispersion of claim 11 wherein the terminal hydroxy group is the onlyhydroxy group in the molecule.
 13. The water dispersion of claim 1wherein the polymer has two terminal hydroxy groups per molecule. 14.The water dispersion of claim 13 wherein the two terminal hydroxy groupsin the polymer are the only hydroxy groups in the polymer.